1. Pediatric Hematology and Oncology, University of Frankfurt, Germany;
2. Department of Pediatric Hematology and Oncology, Hannover Medical School, Germany;
3. Children's Cancer Research Institute, St Anna Kinderspital and Children's Cancer Research Institute (CCRI), Vienna, Austria;
4. 2nd Medical School, Charles University, Prague, Czech Republic;
5. Department of Pediatric Hematology and Oncology, University of Münster, Germany